Selflocking syringe

Abstract

 The invention regards a selflocking syringe. The syringe rod is equipped with an extractor which, when the syringe plunger is pushed to the end of the stroke, hooks the needle and withdraws it by means of a preloaded spring to the inside of the rod, into a protected and inaccessible position, thus making the syringe unserviceable already after its first use.

Description

[0001] The present invention regards selflocking syringes, with particular reference to a syringe with a needle which disappears thus becoming inaccessible after the use of the syringe.

[0002] The dangers originating from the reutilization of already used syringes and the problems caused by the abandonment in public places of used syringes complete with needle are well-known, especially the damages which any prick of these syringes may cause to anybody picks up and inadvertently handles abandoned syringes.

[0003] One of the tasks of the present invention is to eliminate the mentioned dangers and to solve efficaciously the problems caused by syringes, from the one hand by making substantially unserviceable the syringe after its first use and, from the other hand, by getting the syringe needle diasappeared thus preventing it from remaining exposed, which represents a potential danger when abandoning the syringe.

[0004] Another task of the invention is to supply a syringe incorporating some means which, without affecting the normal use of the syringe, are able to withdraw the needle into the plunger automatically so as to make it inaccessible from outside, already after the first use of the syringe. This way, the syringe becomes unserviceable and its needle, being completely hidden, cannot cause any damages.

[0005] The proposed syringe essentially consists of a cylinder ending by a nose to which a needle is applied and of a plunger sliding in the cylinder and equipped with an operation rod. In compliance with the invention, in this syringe:

• the needle is applied to the cylinder nose by means of a needle-holder introduced and extractable from the inside of the cylinder;
• the rod and the plunger have got an axial through hole in which a sliding extractor and a recovery spring are arranged; the spring is connected to this extractor and to a plug applied on the free end, that is the outer end, of the rod;
• the extractor can be displaced from an advanced position, towards the plunger, to a back position; it shows a head protruding axially from the plunger and is conceived to hook the needle-holder when the plunger is pushed deeply into the cylinder;
• in the advanced position, the extractor is integral with the rod and keeps the spring under tension through some hooking means which can be disengaged, at least partially, when the plunger is pushed deeply and the extractor head has hooked the needle-holder;
• after the disengagement of these hooking means, the extractor shifts to the back position by means of the spring in order to withdraw the needle-holder and the needle into the inner part of the rod.

[0006] Advantageously, the forging ends of the recovery spring are let, that is constrained, into the material composing the extractor and the end plug applied on the rod.

[0007] Anyhow, further details about the invention will be more evident in the description given below which refers to the enclosed drawing showing an indicative and non-limiting example of practical realization of the selflocking syringe.

[0008] In this drawing:
   the picture 1 shows, in longitudinal section, the syringe before use and with needle protected by means of a cap;
   the picture 2 shows, in longitudinal section, the syringe in use conditions;
   the picture 3 shows a magnified detail of a part of the syringe marked with a circle in the picture 1;
   the picture 4 shows, in longitudinal section, the syringe after use, that is with withdrawn needle;
   the picture 5 shows an example of the equipment used to make ready the plunger with extractor rod and recovery spring.

[0009] The syringe at issue essentially consists of a hollow cylinder 10, a needle 11 and a plunger 12 with a respective operation rod 13.

[0010] The cylinder 10 shows at the back a seizing flange 10a and ends on the front side by a nose 10b to which the needle 11 is applied. This needle is applied to a needle-holder 11a which is introduced like a plug into a seat defined by the nose 10b from the inside of the cylinder 10 and which is extractable, as stated below, towards the inside of the cylinder. The plunger 12 slides with tightness into the cylinder 10 and is steadily constrained, in 12a, to the rod 13 which extends and protrudes towards the rear side of the cylinder, beyond the seizing flange 10a.

[0011] The rod 13 and the plunger 12 are provided with an axial through hole 14 in which an extracting element 15 and a recovery spring 16 are assembled. The extractor 15 can slide in this through hole 14 and shift from an advanced position, at the same level as the plunger 12, to a back position, far from the plunger. The opposite ends of the recovery spring 16 are respectively fastened to the extractor 15 and to a plug 17 applied on the free, that is rear, end of the rod 13. Advantageously, the forging ends of the recovery spring 16 are let, and so fastened, into the material composing the extractor 15 and the end plug 17. Therefore, the three component parts 15, 16, 17 remain permanently connected and can be handled and assembled jointly and easily.

[0012] In its advanced position, the extractor 15 is integral with the rod 13 and keeps the spring 16 loaded since the latter is stretched, having its opposite end fastened and clamped with the plug 17, as it is possible to infer from the pictures 1 and 2 of the drawing.

[0013] For its stop in the advanced position, the extractor 15 is provided with a peripheral step 15a - picture 3 - which engages itself in the shoulder collar 14a obtained in the hole 14 of the rod 13 thus normally preventing the extractor 15 from shifting backwards. Furthermore, this extractor is equipped with a hooking head 15b, for example in the shape of a mushroom, turned towards the needle-holder 11a and protruding from the piston 12 when the extractor is in the advanced position. The hooking head 15b of the extractor 15 must get constrained with the needle-holder 11a when the plunger is pushed deeply into the cylinder. For this constraint, the needle-holder 11a is provided with a rear notch 18 having at least an inner projection 18a, for example annular, with which the hooking head 11b spring joins together when the plunger reaches the end of the stroke.

[0014] In the end, it should be noted that the shoulder collar 14a in the hole 14 of the rod 13 must become deformed, be drawn and destroyed on the step 15a of the extractor 15 when the plunger 12 is pushed deeply into the cylinder and the extractor 15 is hooked to and supported against the needle-holder 11a.

[0015] In the syringe described above, the extractor 15, the spring 16 and the plug 17, connected one with the other, are previously assembled into the rod 13 by means of an equipment 19 such as the one represented in the picture 5 so that the extractor 15 is hooked in the advanced position and the spring 16 is loaded, that is under tension. Such an assembly is carried out with the help of a thrust tool 20 which passes through a hole 17a obtained in the plug 17 and which is supported and pushes against the extractor until it gives rise to the hooking of the latter one to the collar 14a and the introduction of the spring and plug into the rod. The hole 17a of the plug 17 can be closed. Subsequently, after applying the plunger 12 to the rod provided with the described equipment, the whole is introduced into the cylinder 10 already equipped with needle 11.

[0016] The syringe is now ready for packaging and for a following use as a normal syringe.

[0017] However, with this syringe, the needle 11 is withdrawn upon its use to the inside of the rod 13 thus making the syringe unserviceable and the needle inaccessible. As a matter of fact, when the plunger, advancing during the injection, reaches the end of the stroke, the head 15b of the extractor 15 spring hooks the needle-holder and, when pushing on the rod deeply, the collar 14a in the rod 13 on the step 15a of the extractor itself becomes deformed and is drawn. Then, the extractor, no longer constrained to the rod 13, is shifted to the back position by means of the preloaded recovery spring 16 and pulls away the needle hooked through the needle-holder, as shown in the picture 4 of the drawing.

Claims

1. Selflocking syringe, comprising a hollow cylinder (10) ending by a nose (10b) to which a needle (11) is applied, and a plunger (12) sliding in the cylinder and having an operation rod (13), characterized by the fact that:

- the needle (11) is applied to the nose (10b) of the cylinder (10) by means of a needle-holder (11a) which is introduced and can be extracted from the inside of this cylinder;

- the rod (13) and the plunger (12) have got an axial through hole (14) in which a sliding extractor (15) and a recovery spring (16) are assembled; the latter is connected to the extractor and to a plug (17) applied on the free end of the mentioned rod;

- the mentioned extractor (15) can be displaced from an advanced position, towards the plunger, to a back position and is equipped with a hooking head (15a) which, with extractor in the advanced position, protrudes from the plunger and must hook the needle-holder (11a) when the plunger is pushed deeply into the plunger;

- in the advanced position, the extractor is integral with the rod (13) thus keeping the spring under tension through some hooking means (14a, 15a) which can be disengaged, at least partially, when the plunger is pushed deeply and the head (15a) of the extractor has hooked the needle-holder; and

- the extractor shifts to the back position with the help of the recovery spring (16) after the disengagement of the mentioned hooking means (14a, 15a) to withdraw the needle-holder with the needle to the inside of the rod.

2. Selflocking syringe according to claim 1), in which the opposite ends of the recovery spring (16) are let and constrained into the material composing the extractor and the plug.

3. Selflocking syringe according to claim 1), in which the mentioned plug (17) is provided with a hole (17a) for the passage of a thrust tool on the extractor and for loading the recovery spring.

4. Selflocking syringe in accordance with claims 1) and 2), in which the extractor (15) is provided with a peripheral step (15a) interacting with a shoulder collar (14a) in the hole (14) of the rod to hook the extractor in the advanced position and with loaded recovery spring; this shoulder collar (14) disengages itself when the plunger is pushed to the end of the stroke.

5. Selflocking syringe in accordance with claims 1) and 2), in which the hooking head (15a) engages itself in a notch obtained in the needle-holder and provided with a projection (18a) in which the head spring engages itself.

Drawing